/**
 * Handles opening of and synchronization with the reveal.js
 * notes window.
 *
 * Handshake process:
 * 1. This window posts 'connect' to notes window
 *    - Includes URL of presentation to show
 * 2. Notes window responds with 'connected' when it is available
 * 3. This window proceeds to send the current presentation state
 *    to the notes window
 */
var RevealNotes = (function () {

    function openNotes(notesFilePath) {

        if (!notesFilePath) {
            var jsFileLocation = document.querySelector('script[src$="notes.js"]').src;  // this js file path
            jsFileLocation = jsFileLocation.replace(/notes\.js(\?.*)?$/, '');   // the js folder path
            notesFilePath = jsFileLocation + 'notes.html';
        }

        var notesPopup = window.open(notesFilePath, 'reveal.js - Notes', 'width=1100,height=700');

        // Allow popup window access to Reveal API
        notesPopup.Reveal = this.Reveal;

        /**
         * Connect to the notes window through a postmessage handshake.
         * Using postmessage enables us to work in situations where the
         * origins differ, such as a presentation being opened from the
         * file system.
         */
        function connect() {
            // Keep trying to connect until we get a 'connected' message back
            var connectInterval = setInterval(function () {
                notesPopup.postMessage(JSON.stringify({
                    namespace: 'reveal-notes',
                    type: 'connect',
                    url: window.location.protocol + '//' + window.location.host + window.location.pathname + window.location.search,
                    state: Reveal.getState()
                }), '*');
            }, 500);

            window.addEventListener('message', function (event) {
                var data = JSON.parse(event.data);
                if (data && data.namespace === 'reveal-notes' && data.type === 'connected') {
                    clearInterval(connectInterval);
                    onConnected();
                }
            });
        }

        /**
         * Posts the current slide data to the notes window
         */
        function post(event) {

            var slideElement = Reveal.getCurrentSlide(),
                notesElement = slideElement.querySelector('aside.notes'),
                fragmentElement = slideElement.querySelector('.current-fragment');

            var messageData = {
                namespace: 'reveal-notes',
                type: 'state',
                notes: '',
                markdown: false,
                whitespace: 'normal',
                state: Reveal.getState()
            };

            // Look for notes defined in a slide attribute
            if (slideElement.hasAttribute('data-notes')) {
                messageData.notes = slideElement.getAttribute('data-notes');
                messageData.whitespace = 'pre-wrap';
            }

            // Look for notes defined in a fragment
            if (fragmentElement) {
                var fragmentNotes = fragmentElement.querySelector('aside.notes');
                if (fragmentNotes) {
                    notesElement = fragmentNotes;
                } else if (fragmentElement.hasAttribute('data-notes')) {
                    messageData.notes = fragmentElement.getAttribute('data-notes');
                    messageData.whitespace = 'pre-wrap';

                    // In case there are slide notes
                    notesElement = null;
                }
            }

            // Look for notes defined in an aside element
            if (notesElement) {
                messageData.notes = notesElement.innerHTML;
                messageData.markdown = typeof notesElement.getAttribute('data-markdown') === 'string';
            }

            notesPopup.postMessage(JSON.stringify(messageData), '*');

        }

        /**
         * Called once we have established a connection to the notes
         * window.
         */
        function onConnected() {

            // Monitor events that trigger a change in state
            Reveal.addEventListener('slidechanged', post);
            Reveal.addEventListener('fragmentshown', post);
            Reveal.addEventListener('fragmenthidden', post);
            Reveal.addEventListener('overviewhidden', post);
            Reveal.addEventListener('overviewshown', post);
            Reveal.addEventListener('paused', post);
            Reveal.addEventListener('resumed', post);

            // Post the initial state
            post();

        }

        connect();

    }

    if (!/receiver/i.test(window.location.search)) {

        // If the there's a 'notes' query set, open directly
        if (window.location.search.match(/(\?|\&)notes/gi) !== null) {
            openNotes();
        }

        // Open the notes when the 's' key is hit
        document.addEventListener('keydown', function (event) {
            // Disregard the event if the target is editable or a
            // modifier is present
            if (document.querySelector(':focus') !== null || event.shiftKey || event.altKey || event.ctrlKey || event.metaKey) return;

            // Disregard the event if keyboard is disabled
            if (Reveal.getConfig().keyboard === false) return;

            if (event.keyCode === 83) {
                event.preventDefault();
                openNotes();
            }
        }, false);

        // Show our keyboard shortcut in the reveal.js help overlay
        if (window.Reveal) Reveal.registerKeyboardShortcut('S', 'Speaker notes view');

    }

    return {open: openNotes};

})();
